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Causes of Dim Headlights in a Car and How to Fix Them?


Headlights are necessary for automotive lighting. It helps the drivers to have a proper view of the road ahead in adverse weather conditions, such as night, fog, rain, snow, and other types of bad weather. Moreover, it also helps other drivers to see your car in congested traffic at night. But with the usage, the problem of dim headlights arises in your car.

If you find that the brightness of your headlights is varying or getting dimmer all of a sudden, your automobile needs attention. In the following blog, we will discuss the various causes of dim headlight problems and how you can fix dim lights on your car.

What Are the Main Reasons for Dim Headlights?

You can look at a few things to improve your headlights seems dim, yellow, or do not shine brightly enough. Irrespective of the vehicle you drive, these are the main concerns that make your car headlights lose brightness.

Problems in Car Wiring

If you are facing an issue with dim headlights in your car, then there may be a problem with the car wiring. A variety of electrical parts work together to brighten your headlight bulb. It contains a wiring harness and a fuse in the majority of automobiles. The wiring harness and electrical components generate and supply the power to the car’s front lights. So, when your car’s front lights dim, it can be due to malfunctioning electrical wiring. 

Old Bulbs

The most obvious reason your car headlights are getting dimmer is old headlight bulbs. Various best aftermarket headlights are available, but each comes with a certain lifespan. With excess use, the headlight bulbs burnt out. Most cars have halogen bulbs, and with time, looses their power. It could also be due to inefficient power, design flaw, or due to loose filaments.

Foggy Headlight Lenses

However, burned-out bulbs are not the only reason why their headlights are fading. In actuality, the lenses themselves could be at fault. Acrylic is used to make headlight lenses, the plastic components that encase the bulbs. UV radiation and this substance are known to chemically react with one another. Oxidation is most likely to blame if you see a yellow discoloration or if the lens appears murky or foggy. So, even if your headlight bulbs are brand-new, this will make them appear weak.

Bad Alternator

Another reason your car headlight gets faint is a bad alternator. In a car, the drive belt powers the alternator. If the alternator fails, a car is not going to function correctly. Usually, when the driver starts the engine, the headlights get brighter, and after that, they get dimmer. It indicates that your alternator is not supplying enough power supply. So, a problem with your alternator will cause difficulty in power supply to the electrical systems, consequently affecting your headlights.

Loose Alternator Belt

Sometimes your car has a proper alternator, but still, your car is having feeble headlight problems.

Pulley and alternator belts run in a sequence, and both are connected to the engine. It helps maintain a continuous supply of power. When the alternator belts start slipping or become loose, there will be an insufficient power supply.  Making the car headlights its first suspect of poor supply of energy.

How to Resolve Dim Headlight Problems?


A few simple checks and methods can quickly achieve troubleshooting the fuzzy headlights of your car.

If your car has a blown headlight bulb, then it is best to replace it with a new one. You can choose either HID headlights or LED headlights. It is an easy task. Remove the headlight cover, then turn the blown bulb out of the socket and replace it with the new one.

Another problem was of oxidation of the headlight cover. As with the burning of halogen bulbs, gases are released, making the headlight lens hazy. So, an easy solution is to take out the cover and clean it with a good cleaning solution.

Car wiring can be complex as it requires a good understanding of the wiring harness layout. As mentioned earlier, headlights are dimming while driving can also arise due to poor alternators or loose belts. So, it is advisable to visit a nearby mechanic if you detect a fault in the electrical wiring or alternator.


How do I brighten my headlights?

The easiest way to brighten your headlights is to replace them with new LED headlights or HID. You can also use a headlight restoration kit to clean your headlights.

What could be the possible reason my car headlight is not bright?

If your car faces dim headlights, then the likely reason is the dying headlight bulb. You can replace the bulb to resolve the issue.

Can dim headlights be caused by a damaged fuse?

Fuses are used to protect every electrical component, including the headlights, in your car. When more power passes through them, they blow themselves to interrupt the circuit.  It safeguards every element of the circuit. Therefore, headlights can stop functioning if a fuse for them blows.

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